Abcs Of Networking

05B­EE  INTRODUCTION TO COMPUTER

ASSIGNMENT

ABCs of Networking

TAIMUR   05B‐001‐EE  HARIS        05B‐003‐EE  DANISH     05B‐004‐EE   

Table of Contents 1

OVERVIEW .................................................................................................... 1

2

WHAT IS A NETWORK? .............................................................................. 2

3

WHAT IS A LAN/WAN? ................................................................................ 3

4

PEER-TO-PEER AND SERVER-CLIENT NETWORK .............................. 5 4.1 4.2 4.3

5

PEER-TO-PEER NETWORK ............................................................................ 5 SERVER-CLIENT NETWORK ......................................................................... 6 SUMMARY .................................................................................................. 6

NETWORK OPERATING SYSTEMS .......................................................... 7 5.1 NOVELL NETWARE..................................................................................... 7 5.2 WINDOWS SERVER...................................................................................... 7 5.3 UNIX ......................................................................................................... 7 5.3.1 Solaris ................................................................................................ 8 5.3.2 Mac OS X Server ................................................................................ 8 5.3.3 Linux .................................................................................................. 8 5.4 OS/400....................................................................................................... 9

6

OPEN SYSTEMS INTERCONNECTION MODEL ....................................10

7

BASIC LAN COMPONENTS........................................................................13 7.1 NETWORK SERVER.....................................................................................13 7.2 COMPUTERS AND OTHER PERIPHERALS .......................................................13 7.3 CABLE (MEDIA) .........................................................................................14 7.3.1 Twisted Pair Cable ............................................................................14 7.3.2 Coaxial Cable ...................................................................................14 7.3.3 Fibre Optic Cable .............................................................................15 7.3.4 Summary ...........................................................................................17 7.4 NIC ...........................................................................................................17 7.5 NETWORK INTERCONNECTION HARDWARE .................................................18 7.5.1 Repeater ............................................................................................18 7.5.2 Hub ...................................................................................................18 7.5.3 Bridge ...............................................................................................19 7.5.4 Switch ...............................................................................................19 7.5.5 Router ...............................................................................................20 7.5.6 Gateway ............................................................................................20 7.5.7 Summary ...............................................................................................21

APPENDIX - OSI MODEL & PROTOCOLS ......................................................22 REFERENCES .......................................................................................................23

SEMESTER-1

05B-EE (A)

1 OVERVIEW What is this module about? We will talk about the basic concept of network connectivity in this module. Why we need to know about network connectivity? It's unlikely that any business would purchase an MFP (Multi-Function Product), to connect to a single computer, or just to be used as a stand-alone copier. A high-end, versatile piece of equipment like an MFP is almost certainly going to be connected to a network. To successfully sell an MFP, in fact to even have an intelligent discussion with your prospect’s Information Systems professional, you need to have an understanding of computer networks so to propose a configuration to better meet your prospect’s needs.

Chapter Summary In chapter “What is Network?”, we will discuss about the usage of network. Chapter “What is a LAN/WAN?” shows the difference of LAN and WAN. “Peer-to-peer and Client/Server” In this chapter, we will define the role of the devices in the network, as server, client or peer. “Network Operating Systems” shows some major operating systems used for network. “OSI (Open Systems Interconnection Model)” is the primary architectural model that defines the international standard for network communications products and protocols. “Basic LAN components” introduces network server, computers and peripherals, cable, and commonly used network interconnection hardware.

1

2 WHAT IS A NETWORK? Telephone allows people to communicate with each other who are far apart. Network allows computers, servers, mainframes, and other peripherals (such as printers,

scanners,

multifunction

products,

etc.) to communicate. Each of these devices that is connected to the network is called a node. It also makes sharing (such

of as

information text,

pictures,

sounds, etc.) possible among computers.

If you were to break a network down into its simplest component, you would have 2 pieces. ¾ Physical network – the wiring, network cards, computers and other equipments the network uses to transmit data. ¾ Logical network – the logical arrangement or rule that allows these physical pieces to work together.

2

3 WHAT IS A LAN/WAN? A LAN (Local Area Network) is a network that connects data processing equipments (mainly consisting of computers) within a building site. Many people mistake LAN as a small network as LAN is usually described as "a network within an office”. However, LANs are not necessarily small. LAN can refer to: ¾ A small network linking two personal computers at home, ¾ A network linking several personal computers in a room of a building, ¾ A large network linking all the equipments in a university, a factory, or an office building.

. Figure 3.1: Different size of LAN

To the contrary, a network that covers a wide area by linking few building or LAN sites (for example, Singapore, Kuala Lumpur, Jakarta, Phnom Penh and Bangkok) is called a WAN (Wide Area Network). Computers connected to a WAN are often connected through public networks, such as the PSTN1 (Public Switched Telephone Network). They can also be connected through leased lines or satellites. The largest WAN in existence is the Internet. 1

The international telephone system based on copper wires carrying analogue voice data. This is in contrast to newer telephone networks base on digital technologies, such as ISDN and FDDI.

3

Figure 3.2: LAN

Figure 3.3: WAN

4

4 PEER-TO-PEER AND SERVER-CLIENT NETWORK If multiple PCs are connected in a network, a PC can access the hard disk of the other PC or use the printer connected directly to the other PC2. There are three basic roles that a computer will assume on a network: ¾ Client – A client will utilize, but not provide, network resources. ¾ Peer – A peer can utilize and provide network resources. ¾ Server – A server generally provides, but does not utilize, network resources. The two types of networks for the three roles to communicate are Peer-to-Peer Network and Server-Client Network.

4.1

PEER-TO-PEER NETWORK

Computers are connected to a network with equal rights of access. Users must configure their PCs by themselves about who can access to what resources (such as hard disk or printer that are connected to their computers). Each user assumes the responsibility of operating a network.

/

Increasing the numbers of network users make it more difficult to operate the network.

Figure 4.1: Peer-to-Peer Network

2

Provided the owner shares the resources (e.g. hard disk or printer) to the other users in the network.

5

4.2

SERVER-CLIENT NETWORK

This architecture is suitable for offices with many users as it eliminates a lot of hassles and annoyances when the user group grows. A server machine is installed to control the network operation. This server works as the centerpiece of the network. It provides access to network resources through

centralised

administration

and security.

There

is

a

network

administrator to manage the server and control how each client machine uses the network.

Figure 4.2: Server-Client Network

4.3

SUMMARY Peer-to-Peer

Service-Client

Setup

- Simple and easy to introduce.

- Careful planning is needed.

Introduction cost

- The introduction costs are low.

- The introduction costs are high because the system requires: - Expensive server machine - Network administrator.

Administrator

- Not needed. - Each network user maintains own PC’s networking functions.

- A network administrator is needed to manage the server and network.

Security

- Poorer in terms of security.

- Provide higher quality security.

Suitable for

- Small LANs with several PCs.

- Medium to large LANs used by companies.

6

5 NETWORK OPERATING SYSTEMS The NOS (Network Operating System) in a LAN network works together with the desktop operating system. It is more complicated and has more responsibilities than the OS for a PC. NOS is responsible: ¾ To prepare data that will be transmitted along the network cable between devices ¾ To administrate sharing of files and other network resources, such as printers and scanners. ¾ For security, ensuring that unauthorized users do not access the system. In ABCs of Basic Computer, we have learnt some commonly used OS for personal computers. Here are some commonly NOS used for servers.

5.1

NOVELL NETWARE

In 1984, Novell introduced NetWare, the first software-based network operating system that is specifically designed to run on network servers. In the 20 years since then, Novell has continually set the standard for enterprise-class security, reliability, manageability and cross-platform interoperability [5]. Latest release is NetWare 6.5.

5.2

WINDOWS SERVER

¾ From Microsoft. It is the Windows for servers. ¾ Latest product is Windows Server 2003 Family (a.k.a.3 Windows NT 5.2 and for a time called "Windows.NET server"), released in July 2003.

5.3

UNIX

UNIX was originally developed by AT&T’s Bell Laboratories in the late 1960s [7] [8]. It is widely used in universities, research institutes, government bodies and computer companies due to its portability, flexibility, and power.

3

A.k.a.= Also known as

7

UNIX is nowadays available in various versions from different companies. Each has customized UNIX to do many specialized tasks and utilities. The most well known ones are Sun Solaris, Mac OS X, and Linux.

5.3.1

SOLARIS

¾ From Sun Microsystems ¾ 1st release (Solaris 1, a.k.a. SunOS 4.1.1) in November 1990. Latest version Solaris 10 was released in February 2004 [9].

5.3.2

MAC OS X SERVER

¾ From Apple, used for Macintosh servers. ¾ Unix-based OS with their Macintosh GUI ¾ 1st release of Mac OS X Server 1.0 in March 1999. The latest version is Mac OS X Server 10.3.2, released in December 2003 [9].

5.3.3

LINUX

¾ Originally created by Linus Torvald on 1st Aug 1991 [3]. ¾ Open source4 and is freely available to everyone [3]. ¾ There are now literally hundreds of companies and organizations and an equal number of individuals that have released their own versions of operating systems based on the Linux kernel5. This has contributed to the fast growth of Linux [3]. ¾ IBM, Novell, Sun Microsystems, Hewlett-Packard and other giants of the computing world have embraced Linux and support its ongoing development [3]. ¾ More than a decade after its initial release, Linux is now being adopted worldwide as a server platform primarily. Its use as a home and office desktop operating system is also on the rise [3]. ¾ Latest release is Linux 2.6.5, on 3rd April 2004 [9].

4

All software is built with source code. Open source means the code can be seen and changed.

5

It is this kernel that forms the base around which a Linux operating system is developed.

8

5.4

OS/400

¾ IBM OS for its AS/400 and AS/400e line of midrange servers [2].

¾ AS/400 was formally renamed as “eServer iSeries”, but it is still commonly known as AS/400 [2]. ¾ OS/400 is closely attuned to the AS/400 hardware design and generally comes as part of the basic package, thus there is no alternative operating system to compete with it [2]. ¾ Latest version: OS/400 Version 5 Release 2 [11].

9

6 OPEN SYSTEMS INTERCONNECTION MODEL In order for data transfer over a network to be successful, all hardware and software must work together and communicate in a common "language". Thus, the OSI (Open Systems Interconnection) model was developed and officially adopted as an international standard by the International Organization of Standards (ISO) in 1984. It is now the primary architectural model for network communications. Most of the network communication protocols and networking products used today are compliant with the OSI model [13]. DO NOT confuse ISO with OSI.

ISO => an organisation, a group of people OSI => a standard, a bunch of documents

Computer 1 (Sending)

Computer 2 (Receiving)

DATA

Application

Application

DATA

I DATA

Presentation

Presentation

I DATA

II DATA

Session

Session

II DATA

III DATA

Transport

Transport

III DATA

IIII DATA

Network

Network

IIII DATA

IIIII DATA

Data Link

Data Link

IIIII DATA

IIIIII DATA

Physical

Physical

IIIIII DATA

Figure 6.1: The OSI Model [12]

10

The multi-coloured figure above shows the following concepts: 1. The OSI Model divides data communication between two end points in a telecommunication network into 7 layers. 2. Application layer produces DATA. 3. Each protocol layers adds a header to the data it receives from the layer above it. This is called “encapsulation”. The encapsulated data is transmitted in Protocol Data Units (PDUs). 4. The PDUs are passed down through the stack of layers until they can be transmitted over the Physical Layer. 5. Any layer on one machine speaks the same language as the same layer on any other machine, and therefore can communicate via the Physical layer (this communication is represented by the

Symbols).

6. All information is passed down through all layers until it reaches the Physical layer (represented by the

).

7. The Physical layer chops up the PDUs and transmits the PDUs over the wire. The Physical layer provides the real physical connectivity between machines over which all communication occurs (represented by

)

8. Data passed upwards is un-encapsulated before being passed farther up (coloured bars IIIIII).

11

Table below presents each layer of the OSI Model and its respective functions [1] & [13]. OSI Layer

Function 6

Application Layer (Layer 7)

- Defines interface to user processes for communication and data transfer in network - Provides standardized services such as, file and job transfer and operations

Presentation Layer (Layer 6)

- Usually part of an operating system. - Translates data from Application Layer to a format the Session Layer can understand. - Performs data format conversion. Compresses, decompresses, encodes, decodes, encrypts and decrypts data.

Session Layer (Layer 5)

- Manages user sessions and dialogues - Controls establishment and termination of logic links between users - Reports upper layer errors

Transport Layer (Layer 4)

- Manages the end-to-end message delivery (for example, determining whether all packets have arrived) and error recovery. It ensures complete data transfer.

Network Layer (Layer 3)

- Determines how data are transferred between network devices - Routes and forwarding, addressing, internetworking, error handling, congestion control and packet sequencing.

Data Link Layer (Layer 2)

- Consists of 2 sub layers, LLC and MAC. - Defines procedures for operating the communication links - Detects and corrects packets transmit errors LLC (Logical Link Control) - Controls frame synchronization, flow control and error checking. MAC (Media Access Control) - Controls how a computer on the network gains access to the data and permission to transmit it.

Physical Layer (Layer 1)

- Defines physical hardware connection specifications between network medium and devices - Defines optical, electrical and mechanical characteristics - Responsible for transmitting data across a wire. Table 6.1: OSI Layers

6

This layer is not the application itself, although some applications may perform application layer functions.

12

7 BASIC LAN COMPONENTS Before we learn more about how a network operates, let’s take a look on some basic LAN components [refer to Appendix for their positions in the OSI Model].

7.1

NETWORK SERVER

A network server is essentially a fast computer that has a large hard disk and a fair amount of memory. ¾ It is the centre in the server-client network. ¾ A LAN server controls the usage of the shared resources (e.g. files, storage, application programs, printers, and other devices). The NOS and shared applications are installed in the hard disk on a server. Users access files and applications on the server just as they would access their own hard disks. ¾ Nowadays servers are set up to perform dedicated function, and they are named after the functions, e.g. network server, file server, database server, print server, web server, mail server, etc. [1]

7.2

COMPUTERS AND OTHER PERIPHERALS

Computers and other peripherals, such as printers and scanners, are the clients in a network.

Figure 7.1: Computer and Other Peripherals in LAN

13

7.3

CABLE (MEDIA)

The type of cable chosen is influenced by the network topology used, the layout of the building, and cost. There are 3 common types of network cable.

7.3.1

TWISTED PAIR CABLE

7.3.1.1

UTP

UTP

(Unshielded

Twisted

Pair)

consists of twisted pairs of cable. It resembles telephone wire and is often terminated

with

RJ45

connectors,

which look like a larger version of telephone connectors. The twists in the cable provide protection against radio-frequency interference, which can cause unreliability in the network.

7.3.1.2

STP

STP (Shielded Twisted Pair) also consists of twisted pairs of cable but is covered by a heavy foil

shield

that

protects

it

from

electromagnetic interference. STP provides more protection in areas with heavy machinery or near fluorescent lights.

7.3.2

COAXIAL CABLE

Coaxial cable (like TV cable) is heavier. It used to be the standard for Ethernet, but most new networks use UTP or STP. Coaxial cable is difficult to lay and is not commonly used today. Coaxial cable could be found in older network installations.

14

7.3.3 Fibre

FIBRE OPTIC CABLE optic

(or

optical

fibre)

cable

transmits information as light pulses along a bundle of glass filaments, which is encased in plastic. It can operate in conjunction with any current, or proposed, LAN/WAN standard. Below shows the advantages of fibre optic cables over copper cables [14]. Strength of fibre optic cables Size and Weight

Thinner and lighter

Speed

Operates at high speeds - up into the gigabits per second

Bandwidth

Greater bandwidth, carries more data

Data transmission

Digital transmission (Metal cables transmit data in analogue signal)

Resistant to

- Electromagnetic Interference - Radioactivity

Security/ Eavesdropping

High security. If someone taps into the fibre cable, the continuous pulse of light is disrupted and the signal ends [15].

Reliability

Fast and reliable. Re-transmission of signals is not required for fibre optic cables.

Distance

Signals can be transmitted further without the need to be “refreshed" or strengthened.

Lasting

Not corrode as rapidly as metal cables

Maintenance

Costs much less to maintain

Most telephone company long-distance lines are now fiber optic [2]. The massive Internet and local networking, which demand extremely high bandwidths and reliability, have given fibre optic a chance to stand out among the other media [16].

15

Fibre optic cables used outdoor and indoor have different structure. Outdoor cable must be extremely rugged [16].

Figure 7.2: Lightweight Indoor Fibre Optic Cable

Figure 7.3: Outdoor Fibre Optic Cable

16

7.3.4

SUMMARY

Different network topologies (Ethernet, FDDI, and Token Ring) can use various types of cable (UTP, STP, coaxial, and fibre optic), though certain networks are associated with certain types of cable. For example, people generally associate Table 7.1: Media Type Designation7 [2] Transmission Speed (Mbps)

Base band 8 signalling

Physical medium that carries the signal

10

Base

2

Thin-wire coaxial cable with a maximum segment length of 185 meters

10

Base

5

Thick-wire coaxial cable with a maximum segment length of 500 meters

10

Base

36

Broadband coaxial cable carrying multiple base band channels for a maximum length of 3,600 meters

10

Base

T

Twisted-pair cable (usually UTP)

100

Base

T4

4 pairs of telephone twisted pair wires

100

Base

TX

2 pairs of data grade twisted-pair wire

10

Base

F

Fibre optic cable

100

Base

FX

Two-strand fibre optic cable

Ethernet with coaxial and UTP wiring, while FDDI is associated with fibre optic cable. DO NOT confuse Mbps with MBps. Mbps = Mega bits per second (used to measure bandwidth on a telecommunication medium) MBps = Mega Bytes per second (used to measure data transfer to and from a computer storage device)

7.4

NIC

To connect computers or other devices to a network, you need to install a NIC (Network Interface Card) for each of these devices. This card helps to move data 7

This designation is an IEEE shorthand identifier.

8

Base band signalling means only Ethernet signals are carried on the medium

17

out of the computer or device and onto the network cable, so it can be transmitted to another device on the network. The choice of the NIC to be installed depends on the network topology and the type of network cable used. All the devices on the same network segment (or area) must have the same type of NIC (i.e.9 Ethernet network devices must have Ethernet NICs, etc.). Just as a ship cannot dock at an airport, a Token Ring NIC cannot transmit or read Ethernet data.

Figure 7.4: Typical NIC for Laptop Computer Figure 7.5: Typical NIC for peripheral devices

7.5

NETWORK INTERCONNECTION HARDWARE

7.5.1

REPEATER

Repeaters are used to regenerate analogue or digital signals that are distorted by transmission loss. Analogue repeaters usually can only amplify the signal while digital repeaters can reconstruct a signal to near its original quality [2].

7.5.2

HUB

Hubs are commonly used

to

connect

nodes in a network or segments of a LAN. Both repeaters and hubs are OSI model Layer 1 devices. They simply amplify and transfer the received signals to the next segment, without identify the destination it is intended too. They cannot do the intelligent routing that is performed by bridges and routers [2].

9

abbr. of Id est in Latin: means “that is”.

18

7.5.3

BRIDGE

A bridge links two or more LANs that use the same protocol together [2]. When bridge receives data, it: 1. Identifies if the MAC (Media Access Control) address10 in the data packet is on the left or right side of the bridge. 2. Forward the data to the intended MAC address. That is, if the receiver PC is on the same segment of the sender PC, bridge will not forward the message to the other segment [17].

Figure above shows: ¾ Without bridge: Network A is not linked to Network B. Computer A can only send data to Computer B, but not Computer C and D. ¾ With bridge: Network A is linked to Network B. Computer A can send data to not only Computer B, but also Computer C & D.

7.5.4

SWITCH

Just like bridge, switch channels incoming data from any of multiple input ports to the specific output port that will take the data toward its intended destination. While bridge works at OSI model layer 2, switch works at Layer 2 or Layer 3, depending on the type of network [2].

10

Note: MAC address is NOT the IP address. MAC address is your computer's unique hardware number [2][2].

19

¾ In an Ethernet LAN: a switch determines the destination from the MAC address (device physical address) in each incoming data frame – OSI model Layer 2. ¾ In the Internet (Wide Area Network or WAN): a switch determines the destination from the IP address in each data packet – OSI model Layer 3. Layer 3 switches also perform routing functions, and are called IP switches.

7.5.5

ROUTER

Routers are located at gateways, the places where two or more networks connect [20]. Compared to bridge, router works at OSI model Layer 3 (higher level) and is able to perform more complex analysis to determine the best path [20]between 2 nodes in the network by creating/maintaining/analysing a table (known as routing table) of the available routes. [2]

7.5.6

GATEWAY

Gateway is like very smart router. It connects different types of networks, by translating messages from one protocol to another [1] [2]. Sometimes known as “protocol converter” [18]. For

What it serves as …

Home Users

The ISP (Internet Service Provider) that connects the user to the Internet.

Enterprise Users

The proxy server and firewall that routes the traffic from a workstation to the outside network that is serving the Web pages.

The gateway is also associated with both ¾ Router, which determines where packets are sent, ¾ Switch, which provides the actual path for the packet in and out of the gateway.

20

7.5.7

SUMMARY

NETWORK A

Linking Device

NETWORK B

Application

Application

(Layer 7)

(Layer 7)

Presentation

Presentation

(Layer 6)

Gateway

Session

(Layer 6)

Session

(Layer 5)

(Layer 5)

Transport

Transport

(Layer 4)

(Layer 4)

Network

Switches/Router

(Layer 3)

Data Link

Bridge

(Layer 2)

Physical

Repeater / Hub

(Layer 1)

Network (Layer 3)

Data Link (Layer 2)

Physical (Layer 1)

Figure 7.6: Inter-networking Devices and OSI Model

As you can see, bridge, switch, router and gateway have quite similar function – forwarding the package to the destination node. The major differences are: ¾

¾

¾

Different OSI model layer -

Identify destination by MAC address or IP address

-

Hardware or software level of support

Different complexity -

Identify the available routes

-

Identify best routes (be it shorter path or faster traffic)

-

Support larger network

Different in price

Figure 7.7 shows the positioning of the inter-networking devices in the OSI Model. It Illustrates the OSI higher-layer device can serve the lower layers, e.g. a gateway can be used in place of a router in a network.

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APPENDIX - OSI MODEL & PROTOCOLS OSI Layers

TCP/IP Internet

Novell Netware

Application (Layer 7)

DHCP (Dynamic Host Configuration Protocol), DNS (Domain Name Systems), FTP (File Transfer Protocol), HTTP (HyperText Transfer Protocol), Telnet (TCP/IP Terminal Emulation Protocol), URL (Uniform Resource Locator)

Microsoft Networking

Apple Computer AppleShare

NCP (Netware Core Protocols)

Presentation (Layer 6)

BGMP (Border Gateway Multicast Protocol)

Session (Layer 5)

LDAP (Lightweighted Directory Access Protocol)

Transport (Layer 4)

TCP (Transmission Control Protocol) UDP (User Datagram Protocol)

SPX (Sequenced Packet eXchange)

Network (Layer 3)

IP (Internet Protocol)

IPX (Internet Packet eXchange)

AFP (AppleTalk Filing Protocol), NetBIOS (Network Basic Input/Output System)

NetBEUI (Network Basic Extended User Interface)

PAP (Printer Access Protocol) ATP (AppleTalk Transaction Protocol) DDP (Datagram Delivery Protocol)

Data Link (Layer 2)

Network Interface Cards: Local Talk, Token Ring, FDDI, Ethernet, etc. NIC Drivers: ODI (Open Datalink Interface), NDIS (Network Independent Interface Specification), etc.

Physical (Layer 1)

Transmission Media (Cable): Twisted pair Cable, Coaxial Cable, Fibre Optic Cable, etc.

Table above only shows part of the protocols in each protocol suits. For complete list or further knowledge, you may like to refer to http://www.javvin.com/

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http://www.webopedia.com

[2]

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[3]

http://www.linux.org/info/index.html

[4]

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[5]

http://www.novell.com/products/netware/vp_interview.html

[6]

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[7]

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[8]

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[9]

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[10]

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[11]

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[12]

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[13]

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[14]

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[15]

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[16]

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[17]

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[18]

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[19]

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[20]

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[21]

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[22]

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